P2P programs should come in two flavors: File-Sharing & File-Leeching
This way good old natured file-sharers would become a thriving minority, and leeches & ET-Leechoids would be left to high-strungly rant & leech amongst themselves.
As an added bonus this heartfelt arraignment woul help keep their numbers in check.
You can't beat good ol' natural selection at work.